title: Linking habitat selection and predation risk to spatial variation in survival.
abstract: A central assumption underlying the study of habitat selection is that selected habitats confer enhanced fitness. Unfortunately, this assumption is rarely tested, and in some systems, gradients of predation risk may more accurately characterize spatial variation in vital rates than gradients described by habitat selection studies. Here, we separately measured spatial patterns of both resource selection and predation risk and tested their relationships with a key demographic trait, adult female survival, for a threatened ungulate, woodland caribou (Rangifer tarandus caribou Gmelin). We also evaluated whether exposure to gradients in both predation risk and resource selection value was manifested temporally through instantaneous or seasonal effects on survival outcomes. We used Cox proportional hazards spatial survival modelling to assess the relative support for 5 selection- and risk-based definitions of habitat quality, as quantified by woodland caribou adult female survival. These hypotheses included scenarios in which selection ideally mirrored survival, risk entirely drove survival, non-ideal selection correlated with survival but with additive risk effects, an ecological trap with maladaptive selection and a non-spatial effect of annual variation in weather. Indeed, we found positive relationships between the predicted values of a resource selection function (RSF) and survival, yet subsequently incorporating an additional negative effect of predation risk greatly improved models further. This revealed a positive, but non-ideal relationship between selection and survival. Gradients in these covariates were also shown to affect individual survival probability at multiple temporal scales. Exposure to increased predation risk had a relatively instantaneous effect on survival outcomes, whereas variation in habitat suitability predicted by an RSF had both instantaneous and longer-term seasonal effects on survival. Predation risk was an additive source of hazard beyond that detected through selection alone, and woodland caribou selection thus was shown to be non-ideal. Furthermore, by combining spatial adult female survival models with herd-specific estimates of recruitment in matrix population models, we estimated a spatially explicit landscape of population growth predictions for this endangered species.
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, MT, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: DeCesare
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, MT, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Hebblewhite
authors.affiliation: Parks Canada, Jasper National Park, Box 10, Jasper, Alberta, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Bradley
authors.affiliation: Sustainable Resource Development, Government of Alberta, Grande Prairie, Alberta, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Hervieux
authors.affiliation: Parks Canada, Jasper National Park, Box 10, Jasper, Alberta, Canada.
authors.forename: Lalenia
authors.initials: L
authors.lastname: Neufeld
authors.affiliation: Faculty of Environmental Design, University of Calgary, 2500 University Dr NW, Calgary, Alberta, Canada.
authors.forename: Marco
authors.initials: M
authors.lastname: Musiani
mesh_terms: D000416:Alberta; D000818:Animals; D001955:British Columbia; D017753:Ecosystem; D005260:Female; D020387:Food Chain; D008136:Longevity; D011157:Population Dynamics; D012053:Reindeer / Q000502:physiology*; D062206:Spatial Analysis
keywords: Rangifer tarandus caribou; ecological trap; habitat quality; resource selection functions; species distribution models; survival; wolves; woodland caribou